During mammalian embryogenesis, the first differentiation event that occurs leads to a polarization of the outer cells of the 16-cell morula. This outer layer of cells forms the trophectoderm and the inner, apolar clump of cells become the inner cell mass. The inner cell mass will give rise to:

Answer:

- Hypothesis: thyroxine gene is responsive to low temperatures, thereby its transcript level is higher in cold climates

- Subjects of study: gene expression data collected from individuals from countries with different climates  

- Experiment: to determine thyroxin gene expression level by Real-Time PCR (RT-PCR) in individuals living in cold climates (e.g., Iceland) versus individuals living in warmer climates (e.g., Puerto Rico)

- Independent variable: temperature

- Dependent variable: thyroxin transcript level  

- N sample: 500 individuals of each population  

- Control group: individuals living in the same climate conditions but from different countries. It can be done by collecting gene expression data from individuals living in another country. For example, both Fairbanks (Alaska) in the USA and Reykjavik in Iceland are at 64 degrees N latitude, and thereby these cities have similar climates

- Constant variable: all data collected from individuals of adult age (age range: 20-30 years)  

Explanation:

The scientific method is a sequential process that consists of making hypotheses in order to explain observations from the real world, make predictions based on the working hypotheses, carrying out experiments based on those predictions, test the predictions and draw conclusions based on the results obtained. In an experiment, the independent variable isn't changed by the other variables, while the dependent variable is the variable being measured in the experiment. A constant variable does not change during the experiment. Moreover, a control group is a particular group to which comparisons are made during the experiment (the control group isn't exposed to the independent variable, and therefore any change in the experimental groups can be compared with the control). In this case, it is expected to measure thyroxine expression levels in 500 individuals from each country by RT-PCR (RT-PCR technique is used to measure the amount of mRNA of a target gene of interest). Subsequently, it is possible to determine if the differences in the thyroxin gene expression levels between populations (i.e., individuals living in Iceland vs individuals living in Puerto Rico) are statistically significant to confirm that thyroxin gene activity is increased in response to cold exposure. Finally, the control group can be used to determine if observed differences in gene expression are irrefutably correlated with cold conditions.

Answer:

The frequency of the carriers (heterozygotes) in Massachusetts is 0.018

Explanation:

Due to technical problems, you will find the complete explanation in the attached files

Answer:

The correct answer is C. In North and South America, a majority of the population is located on the coasts.

Explanation:

Historically, the vast majority of civilizations have sought to establish their urban centers around bodies of water, be they rivers or seas, that allow them a rapid expansion outward as well as channels through which to channel trade. Thus, it can be seen how throughout the world and especially the American continent, large cities and population centers are located primarily on the coasts. Examples of this situation are Vancouver in Canada, New York and Los Angeles in the United States, Rio de Janeiro in Brazil or Buenos Aires in Argentina.

Answer:

- Ecological levels to consider in this study: organism, population and community

- Approach: I would use an observational approach to study this bird species

Explanation:

The levels of the ecological organization include the organism, population, community, ecosystem, and biosphere (from simplest to most complex). In this exploratory study, it is imperative to consider: 1-morphological, physiological and behavioral adaptations of the bird species (i.e., organismal-level), 2- size/density/structure of the bird population (i.e., population-level), and 3-interactions between bird population and other populations (i.e., community-level). The higher ecological levels, i.e., ecosystem-level (relationships between the community and abiotic factors ) and biosphere-level (biosphere =  planet Earth), can be in this case disregarded because this study is centered on a focus bird species. Moreover, it is expected to apply an observational strategy because nothing is currently known about the focus bird species. The experimental and modeling approaches seem more suitable to test a particular hypothesis being discussed (it is not the case for this study).

Answer:

Sampling error may allow fixation of one form and the elimination of others in a small population.

Explanation:

It can be seen that in case of a small population size, there are high chances of the elimination or the fixation of the allele in the population when compared to the large population size. Also sampling errors are found in case of small population size that leads to the enhancement of the chances for fixation and also for the elimination of the allele. This large size population doe not have much effect. The random fixation of the either selective allele or the elimination of the disadvantageous allele occurs due to the genetic drift.

SO in order for the population size influenced the survival of both types of mutations , the sampling error may be allowed for the fixation of one of the form and the elimination of the other forms in the small population size.

Answer:

The correct answer is - zero or 0%.

Explanation:

The fertilization in flowering plants takes place by fusing the pollen of one plant or flower with the ovum of another plant or flower of the same species normally and form a zygote. The zygote gets an equal amount of genetic material from both parent plants by the process f exchange of the genetic material.

The ovum or the egg cell of the plant is considered as the mother and the mother is responsible for the chloroplast And mitochondria of the progeny so in this case, the ovum and egg cell comes from the only plant Q thus, the percentage of chloroplast genes provided via Plant R is 0%.

Answer: habitat

Explanation:

It is the only one that makes sense

Answer: a plant that has flowers and produces seeds enclosed within a carpel. The angiosperms are a large group and include herbaceous plants, shrubs, grasses, and most trees.

Explanation:

Answer:

i think its behavioral

Explanation:

Answer:

The answer would be Behavioral Isolation.

Explanation:

I did the Connections Academy Quick Check and it said it was correct.

Answer:

T and A are together

G and C are together

Explanation:

these pairs will always connect to each other

Answer: The main reproductive hormones are estrogen and testosterone. Once a girl enters puberty, estrogen matures the eggs in the ovaries. These are then released at regular intervals during the menstrual cycle. Testosterone stimulates the production of sperm in men.

Explanation:

Answer:

.B

Explanation:

once at the full moon phase

Answer:

small fishes--tuna fish--dead animal material---crabs

Explanation:

follow the arrows from small fishes to crabs

Answer:

Answer is below

Explanation:

Small fish ---> Tuna Fish ---> Dead Animal Material ---> Crabs

This shows the path specifically followed from the small fish to the crabs

Answer:

it think it C ^^^^^^^^^^^^

Answer:

A

Explanation:

Answer:

A, increasing the positive charge of the positively charged object and increasing the negative charge of the negatively charged object

Explanation:

EDGE 2021

Answer:

Tt

Explanation:

Explanation is in the image

Answer:

It should be B

Explanation:

I hope this helps

Answer:

Scalar quantities are quantities that are described only by a magnitude.

Answer:

density-dependent, top-down factor

Explanation:

In biology, limiting factors are resources and other conditions in the environment whose presence/availability limit the population growth rate. Density-dependent factors refer to the conditions whose effects on the size/growth of the population vary depending on the population density. Some examples of density-dependent factors include diseases, competition, and predation, etc. These factors can exhibit a positive or negative correlation with the population size. Moreover, bottom-up population control (species limitation by resources) refers to limitations placed by resources allowing growth (e.g.,  food source or habitat), while top-down population control (limitation by enemies), refers to limitations placed by factors that control the death rate in the population (e.g., predation or diseases).

answer: The global warming controversy concerns the public debate over whether global warming is occurring, how much has occurred in modern times, what has caused it, what its effects will be, whether any action can or should be taken to curb it, and if so what that action should be. In the scientific literature, there is a strong consensus that global surface temperatures have increased in recent decades and that the trend is caused by human-induced emissions of greenhouse gases.[1][2][3][4][5][6] No scientific body of national or international standing disagrees with this view,[7] though a few organizations with members in extractive industries hold non-committal positions,[8] and some have attempted to convince the public that climate change is not happening, or if the climate is changing it is not because of human influence,[9] attempting to sow doubt in the scientific consensus.

Answer:

macronutrients

Explanation:

macronutrients are important for growing plants. the main macronutrients are nitrogen, Potassium, and phosphorus.

Answer:

The second answer.

Explanation:

Answer:

b) is the the answer

Explanation:

hope it helps

Answer:

Tt

Explanation:

Hello. I believe that you are only referring to question 2, since question 3 does not present all the answer options. As such, the offspring of a cross between a tall pea plant (TT) and a low pea plant (tt) would be completely "Tt."

To achieve this result, you must make a Punnett Square, which is a frame that allows you to combine the alleles of the parents in a cross to project the alleles of the offspring.

Alleles are those characterized by the letters associated with characteristics. As you saw in the question above, tall pea plants have "TT" alleles that are dominant alleles, while low pea plants have "tt" alleles that are recessive alleles. In this case, to use Punnett Square, you must put the alleles of one parent in the first row and the allele of the other parent in the first column. Then just combine each allele, as shown below:

    T    T

t    Tt   Tt

t    Tt   Tt

As you can see all the offspring will have the "Tt" alleles. This means that the entire offspring will be tall pea plants. This is because the recessive allele "t", which is related to pea plants, can only be expressed in the presence of another recessive allele. However, the dominant "T" allele, which is associated with tall pea plants, can be expressed in any situation.

Answer:

A gene mutation

Explanation:

DNA nucleotide sequence is unique

Answer:

Womersley numbers :  22.25 , 5.96 , 3.72

Explanation:

Calculate the Womersley number if the heart rate = 70 bpm

For the Human Aorta

∝ = r [tex]\sqrt{\frac{wp}{u} }[/tex]  ------ ( 1 )

r = radius  = 15 mm = 0.015 m

w = 2πf = 2 * π * 70 = 439.82

p = density of blood = 1060 kg/m^3

u = 0.035 P = 3.5 cp = 3.5 * 10^-3 Ns/m^2

Back to equation ( 1 )

∝ = 0.015 * [tex]\sqrt{\frac{439.82*1060}{60*3.5*10^{-3} } }[/tex] = ( 0.015 * √466209.2 / 0.21 )  = 22.35

 For Carotid artery

r = 0.8 cm / 2 = 0.4 cm = 0.004 m

w = 2πf  = 439.82

Womersley number =  ( 0.004 * √466209.2 / 0.21  )

                                = 0.004 * 1489.981 = 5.96

For Femoral artery

r = 0.5 cm / 2 = 0.25 cm = 0.0025 m

Womersley number = 0.0025 * √466209.2 / 0.21  )

                                = 0.0025 * 1489.981 = 3.72

The flow is unsteady because of the varying Womersley numbers

Answer and Explanation:

Many elements can limit population growth. The main elements that can cause this are the lack of resources necessary for the life and development of living beings and the lack of space to be taken by them. In relation to weeds, these resources can be the availability of sun, amount of soil, soil fertility, availability of water and space. However, these plants are very resistant to the lack of these resources, and what most limits their growth is human interference.

Weeds are unfavorable to agriculture and other human activities. This makes humans fight the population growth of these plants using chemical products and even physical strategies. This interference prevents weeds from taking over the world.